1. Field of the Invention
The present invention relates to battery monitoring circuitry and more particularly, but not by way of limitation, to a battery monitoring system that includes an integrated battery holder.
2. Background of the Problem and Related Art
It is well known that a primary battery is a convenient source of power for portable electric and electronic devices. Small size, ease of use, low maintenance and good shelf life are just a few of the reasons that primary batteries are frequently used in modern electronics. For example, primary batteries are regularly used in PCS and servers to keep a time of day clock running even when the particular device is not otherwise powered.
Because the primary battery is such a convenient and reliable source of power, many electronic devices also use the primary battery as a source of backup power, such as for CMOS memoryxe2x80x94thereby preserving the contents of the memory even when the memory is not otherwise powered. In fact, the computer and electronic industry has incorporated the coin-shaped primary battery into the majority of devices that require a backup power source.
Because the primary battery often protects critical data from corruption and loss, a user cannot allow the battery to fail. The failure of a primary battery could mean disastrous data corruption, data loss and/or system downtimexe2x80x94all of which are unacceptable in today""s information critical systems. Accordingly, it is vital that a user or system administrator be able to easily and accurately determine when a primary battery is nearing failure (but not yet completely depleted) and should be replaced.
Furthermore, it is vital that a primary battery be replaceable without corrupting the data it is backing up. In existing devices, replacing a primary cell allows voltage at the backed-up device to float. For example, FIG. 1 illustrates a block diagram of a battery backed, device 105 connected to a primary battery 110 through a supply voltage line 115 and a battery output line 120. The primary battery 110 is also grounded at ground 125. In this device, when the primary battery 110 is removed or inserted, the voltage on line battery output 120 momentarily changes, i.e., floats, and likely creates a condition in the battery backed device 105 that results in data corruption or other damage.
In light of the above-described and other deficiencies in the existing art, a device is needed that accurately monitors the characteristics of a battery, particularly the characteristics of a primary battery used in electronic systems. Furthermore, a device is needed that prevents the voltage on the primary battery""s output line from floating when the battery is replaced.
To remedy the deficiencies of existing systems and methods, the present invention provides, among other things, an apparatus to accurately monitor the characteristics of a battery. Furthermore, the present device prevents the voltage on the primary battery""s output line from floating when the battery is replaced.
In an exemplary embodiment, but by no means the only embodiment, the invention includes a battery clip that is used to secure a battery to a battery connection and a battery monitoring integrated circuit (IC). The battery monitoring IC takes a xe2x80x9cload vs. no-load measurementxe2x80x9d and the results are recorded in a register. When the battery reaches a certain low voltage state, register bits are set and a low battery signal is generated. Furthermore, the exemplary embodiment includes a removal detection circuit both for detecting removal and replacement of the battery and for preventing voltage float on the battery output line.